Folding knife



FIG. 1 is perspective view of the folding knife of my new design;

FIG. 2 is a left side view of the folding knife of my new design;

FIG. 3 is a right side view of the folding knife of my new design,

FIG. 4 is a top view of the folding knife of my new design;

FIG. 5 is a bottom view of the folding knife of my new design;

FIG. 6 is a right or front end view of the folding knife of my new design; and,

FIG. 7 is a left or rear end view of the folding knife of my new design.

The broken lines in the drawings illustrate features that form no part of the claimed design. 

The ornamental design for a folding knife, as shown and described. 